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proper signal handling

--- a/9pex.c

+++ b/9pex.c

@@ -74,6 +74,10 @@

 	[Twstat-Tversion] = "Twstat",

 };

+static char *modes[] = {

+	"read", "write", "rdwr", "exec",

+};

+

 static char *Enoauth = "authentication not required";

 static char *Eunknownfid = "unknown fid";

 static char *Enowstat = "wstat prohibited";

@@ -136,8 +140,15 @@

 	FD_SET(out, &e);

 	memset(&t, 0, sizeof(t));

 	t.tv_usec = 1000;

-	if ((n = select(max(in, out) + 1, &r, &w, &e, block ? NULL : &t)) < 0 || FD_ISSET(in, &e) || FD_ISSET(out, &e))

-		return -1;

+	for (;;) {

+		errno = 0;

+		if ((n = select(max(in, out) + 1, &r, &w, &e, block ? NULL : &t)) < 0 || FD_ISSET(in, &e) || FD_ISSET(out, &e)) {

+			if (errno == EINTR)

+				continue;

+			return -1;

+		}

+		break;

+	}

 	fl = 0;

 	if (FD_ISSET(in, &r))

@@ -156,11 +167,15 @@

 	if (wrend == 0)

 		return 0;

-	for (n = 0; n < wrend && (w = write(out, wrbuf+n, wrend-n)) > 0; n += w);

-	if (w <= 0) {

-		if (errno != EPIPE) /* remote end closed */

-			perror("write");

-		return -1;

+	for (n = 0; n < wrend; n += w) {

+		errno = 0;

+		if ((w = write(out, wrbuf+n, wrend-n)) <= 0) {

+			if (errno == EINTR)

+				continue;

+			if (errno != EPIPE) /* remote end closed */

+				perror("write");

+			return -1;

+		}

 	}

 	if (debug >= 2)

 		trace("<- %d bytes, %d left\n", wrend, wroff-wrend);

@@ -542,13 +557,17 @@

 	used(c);

 	r = 0;

 	*err = 0;

-	for (n = 0; n < size && (r = read(in, rdbuf, size)) > 0; n += r);

-	if (r <= 0) {

-		if (r == 0)

-			eof = 1;

-		else

-			*err = 1;

-		return NULL;

+	for (n = 0; n < size; n += r) {

+		errno = 0;

+		if ((r = read(in, rdbuf, size)) <= 0) {

+			if (r == EINTR)

+				continue;

+			if (r == 0)

+				eof = 1;

+			else

+				*err = 1;

+			return NULL;

+		}

 	}

 	return rdbuf;

@@ -800,6 +819,37 @@

 	}

 }

+static void

+sigdebug(int s)

+{

+	Fid *f;

+	int i, n;

+

+	used(s);

+	n = 0;

+	for (i = 0; i < numfids; i++) {

+		f = fids[i];

+		if (f == NULL)

+			continue;

+

+		fprintf(stderr, "fid %u ", f->fid);

+

+		if (f->dir != NULL)

+			fprintf(stderr, "open mode=dir ");

+		else if (f->fd >= 0)

+			fprintf(stderr, "open mode=%s%s%s ", modes[(f->mode & 0xf)], (f->mode & C9trunc) ? ",trunc" : "", (f->mode & C9rclose) ? ",rclose" : "");

+

+		fprintf(stderr, "qid=[path=%"PRIu64" type=0x%02x version=%"PRIu32"] iounit=%d ", f->qid.path, f->qid.type, f->qid.version, f->iounit);

+		fprintf(stderr, " %s %s\n", f->path, f->name);

+		n++;

+	}

+

+	fprintf(stderr, "fids\t%d\n", n);

+	fprintf(stderr, "tags\t%d\n", numtags);

+	fprintf(stderr, "uids\t%d\n", numuids);

+	fprintf(stderr, "gids\t%d\n", numgids);

+}

+

 int

 main(int argc, char **argv)

 {

@@ -807,6 +857,7 @@

 	char *err;

 	Fid *f;

 	struct parg_state ps;

+	struct sigaction sa;

 	int can, i, c, rdonly, block;

 	parg_init(&ps);

@@ -876,7 +927,16 @@

 	wrbuf = calloc(1, wrbufsz);

 	wroff = wrend = 0;

-	signal(SIGPIPE, SIG_IGN);

+	memset(&sa, 0, sizeof(sa));

+	sa.sa_handler = SIG_IGN;

+	sa.sa_flags = SA_RESTART;

+	sigaction(SIGPIPE, &sa, NULL);

+

+	memset(&sa, 0, sizeof(sa));

+	sa.sa_handler = sigdebug;

+	sa.sa_flags = SA_RESTART;

+	sigfillset(&sa.sa_mask);

+	sigaction(SIGUSR1, &sa, NULL);

 	err = NULL;

 	rdonly = block = 1; /* at first we wait until the client sends in data */